1959 sportsman . Having trouble making it run

[razerface]

What is compression supposed to be? I have 70lb on 150cc engine. Having trouble making it run. It sat for 12 years.

[Ricks]

It should run fine with 70 pounds.  I assume you checked for spark?  Did you put new plugs in it?  What did you set the gap at?  After it wouldn't start, did you remove the compression cover?  If so, did a lot of fuel leak out?

[razerface]

Yes, new plug and it has spark. If 70 lbs is ok, it has to be carb problem i guess. It fires on starting fluid. When it does start, it runs like a hit & miss engine,,clears up and runs until you let off throttle. It must be kicked a couple thousand times to get running.

I cleaned carb. New needles and seats and adjusting screws. May have to take carb back off since junk got in line from tank before i mounted a filter on fuel line.

Where do you set adjusting screws to start with on rebuilt carb?

Please explain the compression cover thing? Just checking for flooding?

[Ricks]

The compression cover is the big cover on the side of the motor. Inside that cover is the compression plate.  If you have a bad needle and seat in a jet or float, a lot of gas will collect in the engine base.  By loosening the side cover, the gas will run out. 

Did you buy a new Carb or rebuild the one you have?  If using a stock carb, turn both screws in all the way, but don't crank on them.  Then open them both 1 turn.  That should get you in the ballpark.  If you bought one of the reproduction carbs, I have found them to need about 1 1/2 turns.

[razerface]

Rebuilt stock carb with all new parts. Single plug cylinder. Does the compression cover need to be sealed tight after checking? I do not have a new gasket.

Is spark usually blue on these? I think mine is a little yellow.

[pd]

Yes , the compression cover needs to be sealed . Maybe apply a little sealer to the gasket .
And , yes , the spark should be blueish . The fatter the better .
Check all electrical connections . They should be clean and scratch tight .
Check the points . They should be clean ( no pits or peaks ) and set at .020" , at least they are on my Phelon magneto .
Also check that the inside of the flywheel is clean , no rust or other coating on the magnets . Likewise the coil core ends should be clean . You might remove the coils and insure a clean , tight mount for good ground ( no corrosion ) .
If you have a VOM , you might measure the coils primary resistance .
My OEM Phelon ignition coil measures 14.11? .
My replacement Cushman ignition coil measured 17.7? out of the box and 17.66? installed .

Hope that^ helps .

Pete .

[Ricks]

Glue the compression gasket to the compression plate with some gasket maker.  This way, when you loosen it, it will not stick to the engine case.

Almost all the problems I’ve encountered with Simplex engines not starting is compression or carburetor.  Like I said in your other thread, I have not had good luck rebuilding these carbs.  The reason for this is people crank the screws in really tight and deform the seat.  Putting in a new needle doesn’t really fix the problem.  I’ve restored 5 bikes over the last 7 years, and I put a reproduction carburetor on every one.  All my bikes run like a top, as witnessed at Portland every year.